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diff --git a/8.31/doc/pcretest.txt b/8.31/doc/pcretest.txt new file mode 100644 index 0000000..2d39fb1 --- /dev/null +++ b/8.31/doc/pcretest.txt @@ -0,0 +1,903 @@ +PCRETEST(1) PCRETEST(1) + + +NAME + pcretest - a program for testing Perl-compatible regular expressions. + + +SYNOPSIS + + pcretest [options] [input file [output file]] + + pcretest was written as a test program for the PCRE regular expression + library itself, but it can also be used for experimenting with regular + expressions. This document describes the features of the test program; + for details of the regular expressions themselves, see the pcrepattern + documentation. For details of the PCRE library function calls and their + options, see the pcreapi and pcre16 documentation. The input for + pcretest is a sequence of regular expression patterns and strings to be + matched, as described below. The output shows the result of each match. + Options on the command line and the patterns control PCRE options and + exactly what is output. + + +PCRE's 8-BIT and 16-BIT LIBRARIES + + From release 8.30, two separate PCRE libraries can be built. The origi- + nal one supports 8-bit character strings, whereas the newer 16-bit + library supports character strings encoded in 16-bit units. The + pcretest program can be used to test both libraries. However, it is + itself still an 8-bit program, reading 8-bit input and writing 8-bit + output. When testing the 16-bit library, the patterns and data strings + are converted to 16-bit format before being passed to the PCRE library + functions. Results are converted to 8-bit for output. + + References to functions and structures of the form pcre[16]_xx below + mean "pcre_xx when using the 8-bit library or pcre16_xx when using the + 16-bit library". + + +COMMAND LINE OPTIONS + + -16 If both the 8-bit and the 16-bit libraries have been built, + this option causes the 16-bit library to be used. If only the + 16-bit library has been built, this is the default (so has no + effect). If only the 8-bit library has been built, this + option causes an error. + + -b Behave as if each pattern has the /B (show byte code) modi- + fier; the internal form is output after compilation. + + -C Output the version number of the PCRE library, and all avail- + able information about the optional features that are + included, and then exit. All other options are ignored. + + -C option Output information about a specific build-time option, then + exit. This functionality is intended for use in scripts such + as RunTest. The following options output the value indicated: + + linksize the internal link size (2, 3, or 4) + newline the default newline setting: + CR, LF, CRLF, ANYCRLF, or ANY + + The following options output 1 for true or zero for false: + + jit just-in-time support is available + pcre16 the 16-bit library was built + pcre8 the 8-bit library was built + ucp Unicode property support is available + utf UTF-8 and/or UTF-16 support is available + + -d Behave as if each pattern has the /D (debug) modifier; the + internal form and information about the compiled pattern is + output after compilation; -d is equivalent to -b -i. + + -dfa Behave as if each data line contains the \D escape sequence; + this causes the alternative matching function, + pcre[16]_dfa_exec(), to be used instead of the standard + pcre[16]_exec() function (more detail is given below). + + -help Output a brief summary these options and then exit. + + -i Behave as if each pattern has the /I modifier; information + about the compiled pattern is given after compilation. + + -M Behave as if each data line contains the \M escape sequence; + this causes PCRE to discover the minimum MATCH_LIMIT and + MATCH_LIMIT_RECURSION settings by calling pcre[16]_exec() + repeatedly with different limits. + + -m Output the size of each compiled pattern after it has been + compiled. This is equivalent to adding /M to each regular + expression. The size is given in bytes for both libraries. + + -o osize Set the number of elements in the output vector that is used + when calling pcre[16]_exec() or pcre[16]_dfa_exec() to be + osize. The default value is 45, which is enough for 14 cap- + turing subexpressions for pcre[16]_exec() or 22 different + matches for pcre[16]_dfa_exec(). The vector size can be + changed for individual matching calls by including \O in the + data line (see below). + + -p Behave as if each pattern has the /P modifier; the POSIX + wrapper API is used to call PCRE. None of the other options + has any effect when -p is set. This option can be used only + with the 8-bit library. + + -q Do not output the version number of pcretest at the start of + execution. + + -S size On Unix-like systems, set the size of the run-time stack to + size megabytes. + + -s or -s+ Behave as if each pattern has the /S modifier; in other + words, force each pattern to be studied. If -s+ is used, all + the JIT compile options are passed to pcre[16]_study(), caus- + ing just-in-time optimization to be set up if it is avail- + able, for both full and partial matching. Specific JIT com- + pile options can be selected by following -s+ with a digit in + the range 1 to 7, which selects the JIT compile modes as fol- + lows: + + 1 normal match only + 2 soft partial match only + 3 normal match and soft partial match + 4 hard partial match only + 6 soft and hard partial match + 7 all three modes (default) + + If -s++ is used instead of -s+ (with or without a following + digit), the text "(JIT)" is added to the first output line + after a match or no match when JIT-compiled code was actually + used. + + If the /I or /D option is present on a pattern (requesting output about + the compiled pattern), information about the result of studying is not + included when studying is caused only by -s and neither -i nor -d is + present on the command line. This behaviour means that the output from + tests that are run with and without -s should be identical, except when + options that output information about the actual running of a match are + set. + + The -M, -t, and -tm options, which give information about resources + used, are likely to produce different output with and without -s. Out- + put may also differ if the /C option is present on an individual pat- + tern. This uses callouts to trace the the matching process, and this + may be different between studied and non-studied patterns. If the pat- + tern contains (*MARK) items there may also be differences, for the same + reason. The -s command line option can be overridden for specific pat- + terns that should never be studied (see the /S pattern modifier below). + + -t Run each compile, study, and match many times with a timer, + and output resulting time per compile or match (in millisec- + onds). Do not set -m with -t, because you will then get the + size output a zillion times, and the timing will be dis- + torted. You can control the number of iterations that are + used for timing by following -t with a number (as a separate + item on the command line). For example, "-t 1000" would iter- + ate 1000 times. The default is to iterate 500000 times. + + -tm This is like -t except that it times only the matching phase, + not the compile or study phases. + + +DESCRIPTION + + If pcretest is given two filename arguments, it reads from the first + and writes to the second. If it is given only one filename argument, it + reads from that file and writes to stdout. Otherwise, it reads from + stdin and writes to stdout, and prompts for each line of input, using + "re>" to prompt for regular expressions, and "data>" to prompt for data + lines. + + When pcretest is built, a configuration option can specify that it + should be linked with the libreadline library. When this is done, if + the input is from a terminal, it is read using the readline() function. + This provides line-editing and history facilities. The output from the + -help option states whether or not readline() will be used. + + The program handles any number of sets of input on a single input file. + Each set starts with a regular expression, and continues with any num- + ber of data lines to be matched against the pattern. + + Each data line is matched separately and independently. If you want to + do multi-line matches, you have to use the \n escape sequence (or \r or + \r\n, etc., depending on the newline setting) in a single line of input + to encode the newline sequences. There is no limit on the length of + data lines; the input buffer is automatically extended if it is too + small. + + An empty line signals the end of the data lines, at which point a new + regular expression is read. The regular expressions are given enclosed + in any non-alphanumeric delimiters other than backslash, for example: + + /(a|bc)x+yz/ + + White space before the initial delimiter is ignored. A regular expres- + sion may be continued over several input lines, in which case the new- + line characters are included within it. It is possible to include the + delimiter within the pattern by escaping it, for example + + /abc\/def/ + + If you do so, the escape and the delimiter form part of the pattern, + but since delimiters are always non-alphanumeric, this does not affect + its interpretation. If the terminating delimiter is immediately fol- + lowed by a backslash, for example, + + /abc/\ + + then a backslash is added to the end of the pattern. This is done to + provide a way of testing the error condition that arises if a pattern + finishes with a backslash, because + + /abc\/ + + is interpreted as the first line of a pattern that starts with "abc/", + causing pcretest to read the next line as a continuation of the regular + expression. + + +PATTERN MODIFIERS + + A pattern may be followed by any number of modifiers, which are mostly + single characters. Following Perl usage, these are referred to below + as, for example, "the /i modifier", even though the delimiter of the + pattern need not always be a slash, and no slash is used when writing + modifiers. White space may appear between the final pattern delimiter + and the first modifier, and between the modifiers themselves. + + The /i, /m, /s, and /x modifiers set the PCRE_CASELESS, PCRE_MULTILINE, + PCRE_DOTALL, or PCRE_EXTENDED options, respectively, when pcre[16]_com- + pile() is called. These four modifier letters have the same effect as + they do in Perl. For example: + + /caseless/i + + The following table shows additional modifiers for setting PCRE com- + pile-time options that do not correspond to anything in Perl: + + /8 PCRE_UTF8 ) when using the 8-bit + /? PCRE_NO_UTF8_CHECK ) library + + /8 PCRE_UTF16 ) when using the 16-bit + /? PCRE_NO_UTF16_CHECK ) library + + /A PCRE_ANCHORED + /C PCRE_AUTO_CALLOUT + /E PCRE_DOLLAR_ENDONLY + /f PCRE_FIRSTLINE + /J PCRE_DUPNAMES + /N PCRE_NO_AUTO_CAPTURE + /U PCRE_UNGREEDY + /W PCRE_UCP + /X PCRE_EXTRA + /Y PCRE_NO_START_OPTIMIZE + /<JS> PCRE_JAVASCRIPT_COMPAT + /<cr> PCRE_NEWLINE_CR + /<lf> PCRE_NEWLINE_LF + /<crlf> PCRE_NEWLINE_CRLF + /<anycrlf> PCRE_NEWLINE_ANYCRLF + /<any> PCRE_NEWLINE_ANY + /<bsr_anycrlf> PCRE_BSR_ANYCRLF + /<bsr_unicode> PCRE_BSR_UNICODE + + The modifiers that are enclosed in angle brackets are literal strings + as shown, including the angle brackets, but the letters within can be + in either case. This example sets multiline matching with CRLF as the + line ending sequence: + + /^abc/m<CRLF> + + As well as turning on the PCRE_UTF8/16 option, the /8 modifier causes + all non-printing characters in output strings to be printed using the + \x{hh...} notation. Otherwise, those less than 0x100 are output in hex + without the curly brackets. + + Full details of the PCRE options are given in the pcreapi documenta- + tion. + + Finding all matches in a string + + Searching for all possible matches within each subject string can be + requested by the /g or /G modifier. After finding a match, PCRE is + called again to search the remainder of the subject string. The differ- + ence between /g and /G is that the former uses the startoffset argument + to pcre[16]_exec() to start searching at a new point within the entire + string (which is in effect what Perl does), whereas the latter passes + over a shortened substring. This makes a difference to the matching + process if the pattern begins with a lookbehind assertion (including \b + or \B). + + If any call to pcre[16]_exec() in a /g or /G sequence matches an empty + string, the next call is done with the PCRE_NOTEMPTY_ATSTART and + PCRE_ANCHORED flags set in order to search for another, non-empty, + match at the same point. If this second match fails, the start offset + is advanced, and the normal match is retried. This imitates the way + Perl handles such cases when using the /g modifier or the split() func- + tion. Normally, the start offset is advanced by one character, but if + the newline convention recognizes CRLF as a newline, and the current + character is CR followed by LF, an advance of two is used. + + Other modifiers + + There are yet more modifiers for controlling the way pcretest operates. + + The /+ modifier requests that as well as outputting the substring that + matched the entire pattern, pcretest should in addition output the + remainder of the subject string. This is useful for tests where the + subject contains multiple copies of the same substring. If the + modi- + fier appears twice, the same action is taken for captured substrings. + In each case the remainder is output on the following line with a plus + character following the capture number. Note that this modifier must + not immediately follow the /S modifier because /S+ and /S++ have other + meanings. + + The /= modifier requests that the values of all potential captured + parentheses be output after a match. By default, only those up to the + highest one actually used in the match are output (corresponding to the + return code from pcre[16]_exec()). Values in the offsets vector corre- + sponding to higher numbers should be set to -1, and these are output as + "<unset>". This modifier gives a way of checking that this is happen- + ing. + + The /B modifier is a debugging feature. It requests that pcretest out- + put a representation of the compiled code after compilation. Normally + this information contains length and offset values; however, if /Z is + also present, this data is replaced by spaces. This is a special fea- + ture for use in the automatic test scripts; it ensures that the same + output is generated for different internal link sizes. + + The /D modifier is a PCRE debugging feature, and is equivalent to /BI, + that is, both the /B and the /I modifiers. + + The /F modifier causes pcretest to flip the byte order of the 2-byte + and 4-byte fields in the compiled pattern. This facility is for testing + the feature in PCRE that allows it to execute patterns that were com- + piled on a host with a different endianness. This feature is not avail- + able when the POSIX interface to PCRE is being used, that is, when the + /P pattern modifier is specified. See also the section about saving and + reloading compiled patterns below. + + The /I modifier requests that pcretest output information about the + compiled pattern (whether it is anchored, has a fixed first character, + and so on). It does this by calling pcre[16]_fullinfo() after compiling + a pattern. If the pattern is studied, the results of that are also out- + put. + + The /K modifier requests pcretest to show names from backtracking con- + trol verbs that are returned from calls to pcre[16]_exec(). It causes + pcretest to create a pcre[16]_extra block if one has not already been + created by a call to pcre[16]_study(), and to set the PCRE_EXTRA_MARK + flag and the mark field within it, every time that pcre[16]_exec() is + called. If the variable that the mark field points to is non-NULL for a + match, non-match, or partial match, pcretest prints the string to which + it points. For a match, this is shown on a line by itself, tagged with + "MK:". For a non-match it is added to the message. + + The /L modifier must be followed directly by the name of a locale, for + example, + + /pattern/Lfr_FR + + For this reason, it must be the last modifier. The given locale is set, + pcre[16]_maketables() is called to build a set of character tables for + the locale, and this is then passed to pcre[16]_compile() when compil- + ing the regular expression. Without an /L (or /T) modifier, NULL is + passed as the tables pointer; that is, /L applies only to the expres- + sion on which it appears. + + The /M modifier causes the size in bytes of the memory block used to + hold the compiled pattern to be output. This does not include the size + of the pcre[16] block; it is just the actual compiled data. If the pat- + tern is successfully studied with the PCRE_STUDY_JIT_COMPILE option, + the size of the JIT compiled code is also output. + + If the /S modifier appears once, it causes pcre[16]_study() to be + called after the expression has been compiled, and the results used + when the expression is matched. If /S appears twice, it suppresses + studying, even if it was requested externally by the -s command line + option. This makes it possible to specify that certain patterns are + always studied, and others are never studied, independently of -s. This + feature is used in the test files in a few cases where the output is + different when the pattern is studied. + + If the /S modifier is immediately followed by a + character, the call + to pcre[16]_study() is made with all the JIT study options, requesting + just-in-time optimization support if it is available, for both normal + and partial matching. If you want to restrict the JIT compiling modes, + you can follow /S+ with a digit in the range 1 to 7: + + 1 normal match only + 2 soft partial match only + 3 normal match and soft partial match + 4 hard partial match only + 6 soft and hard partial match + 7 all three modes (default) + + If /S++ is used instead of /S+ (with or without a following digit), the + text "(JIT)" is added to the first output line after a match or no + match when JIT-compiled code was actually used. + + Note that there is also an independent /+ modifier; it must not be + given immediately after /S or /S+ because this will be misinterpreted. + + If JIT studying is successful, the compiled JIT code will automatically + be used when pcre[16]_exec() is run, except when incompatible run-time + options are specified. For more details, see the pcrejit documentation. + See also the \J escape sequence below for a way of setting the size of + the JIT stack. + + The /T modifier must be followed by a single digit. It causes a spe- + cific set of built-in character tables to be passed to pcre[16]_com- + pile(). It is used in the standard PCRE tests to check behaviour with + different character tables. The digit specifies the tables as follows: + + 0 the default ASCII tables, as distributed in + pcre_chartables.c.dist + 1 a set of tables defining ISO 8859 characters + + In table 1, some characters whose codes are greater than 128 are iden- + tified as letters, digits, spaces, etc. + + Using the POSIX wrapper API + + The /P modifier causes pcretest to call PCRE via the POSIX wrapper API + rather than its native API. This supports only the 8-bit library. When + /P is set, the following modifiers set options for the regcomp() func- + tion: + + /i REG_ICASE + /m REG_NEWLINE + /N REG_NOSUB + /s REG_DOTALL ) + /U REG_UNGREEDY ) These options are not part of + /W REG_UCP ) the POSIX standard + /8 REG_UTF8 ) + + The /+ modifier works as described above. All other modifiers are + ignored. + + +DATA LINES + + Before each data line is passed to pcre[16]_exec(), leading and trail- + ing white space is removed, and it is then scanned for \ escapes. Some + of these are pretty esoteric features, intended for checking out some + of the more complicated features of PCRE. If you are just testing + "ordinary" regular expressions, you probably don't need any of these. + The following escapes are recognized: + + \a alarm (BEL, \x07) + \b backspace (\x08) + \e escape (\x27) + \f form feed (\x0c) + \n newline (\x0a) + \qdd set the PCRE_MATCH_LIMIT limit to dd + (any number of digits) + \r carriage return (\x0d) + \t tab (\x09) + \v vertical tab (\x0b) + \nnn octal character (up to 3 octal digits); always + a byte unless > 255 in UTF-8 or 16-bit mode + \xhh hexadecimal byte (up to 2 hex digits) + \x{hh...} hexadecimal character (any number of hex digits) + \A pass the PCRE_ANCHORED option to pcre[16]_exec() + or pcre[16]_dfa_exec() + \B pass the PCRE_NOTBOL option to pcre[16]_exec() + or pcre[16]_dfa_exec() + \Cdd call pcre[16]_copy_substring() for substring dd + after a successful match (number less than 32) + \Cname call pcre[16]_copy_named_substring() for substring + "name" after a successful match (name termin- + ated by next non alphanumeric character) + \C+ show the current captured substrings at callout + time + \C- do not supply a callout function + \C!n return 1 instead of 0 when callout number n is + reached + \C!n!m return 1 instead of 0 when callout number n is + reached for the nth time + \C*n pass the number n (may be negative) as callout + data; this is used as the callout return value + \D use the pcre[16]_dfa_exec() match function + \F only shortest match for pcre[16]_dfa_exec() + \Gdd call pcre[16]_get_substring() for substring dd + after a successful match (number less than 32) + \Gname call pcre[16]_get_named_substring() for substring + "name" after a successful match (name termin- + ated by next non-alphanumeric character) + \Jdd set up a JIT stack of dd kilobytes maximum (any + number of digits) + \L call pcre[16]_get_substringlist() after a + successful match + \M discover the minimum MATCH_LIMIT and + MATCH_LIMIT_RECURSION settings + \N pass the PCRE_NOTEMPTY option to pcre[16]_exec() + or pcre[16]_dfa_exec(); if used twice, pass the + PCRE_NOTEMPTY_ATSTART option + \Odd set the size of the output vector passed to + pcre[16]_exec() to dd (any number of digits) + \P pass the PCRE_PARTIAL_SOFT option to pcre[16]_exec() + or pcre[16]_dfa_exec(); if used twice, pass the + PCRE_PARTIAL_HARD option + \Qdd set the PCRE_MATCH_LIMIT_RECURSION limit to dd + (any number of digits) + \R pass the PCRE_DFA_RESTART option to pcre[16]_dfa_exec() + \S output details of memory get/free calls during matching + \Y pass the PCRE_NO_START_OPTIMIZE option to pcre[16]_exec() + or pcre[16]_dfa_exec() + \Z pass the PCRE_NOTEOL option to pcre[16]_exec() + or pcre[16]_dfa_exec() + \? pass the PCRE_NO_UTF[8|16]_CHECK option to + pcre[16]_exec() or pcre[16]_dfa_exec() + \>dd start the match at offset dd (optional "-"; then + any number of digits); this sets the startoffset + argument for pcre[16]_exec() or pcre[16]_dfa_exec() + \<cr> pass the PCRE_NEWLINE_CR option to pcre[16]_exec() + or pcre[16]_dfa_exec() + \<lf> pass the PCRE_NEWLINE_LF option to pcre[16]_exec() + or pcre[16]_dfa_exec() + \<crlf> pass the PCRE_NEWLINE_CRLF option to pcre[16]_exec() + or pcre[16]_dfa_exec() + \<anycrlf> pass the PCRE_NEWLINE_ANYCRLF option to pcre[16]_exec() + or pcre[16]_dfa_exec() + \<any> pass the PCRE_NEWLINE_ANY option to pcre[16]_exec() + or pcre[16]_dfa_exec() + + The use of \x{hh...} is not dependent on the use of the /8 modifier on + the pattern. It is recognized always. There may be any number of hexa- + decimal digits inside the braces; invalid values provoke error mes- + sages. + + Note that \xhh specifies one byte rather than one character in UTF-8 + mode; this makes it possible to construct invalid UTF-8 sequences for + testing purposes. On the other hand, \x{hh} is interpreted as a UTF-8 + character in UTF-8 mode, generating more than one byte if the value is + greater than 127. When testing the 8-bit library not in UTF-8 mode, + \x{hh} generates one byte for values less than 256, and causes an error + for greater values. + + In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it + possible to construct invalid UTF-16 sequences for testing purposes. + + The escapes that specify line ending sequences are literal strings, + exactly as shown. No more than one newline setting should be present in + any data line. + + A backslash followed by anything else just escapes the anything else. + If the very last character is a backslash, it is ignored. This gives a + way of passing an empty line as data, since a real empty line termi- + nates the data input. + + The \J escape provides a way of setting the maximum stack size that is + used by the just-in-time optimization code. It is ignored if JIT opti- + mization is not being used. Providing a stack that is larger than the + default 32K is necessary only for very complicated patterns. + + If \M is present, pcretest calls pcre[16]_exec() several times, with + different values in the match_limit and match_limit_recursion fields of + the pcre[16]_extra data structure, until it finds the minimum numbers + for each parameter that allow pcre[16]_exec() to complete without + error. Because this is testing a specific feature of the normal inter- + pretive pcre[16]_exec() execution, the use of any JIT optimization that + might have been set up by the /S+ qualifier of -s+ option is disabled. + + The match_limit number is a measure of the amount of backtracking that + takes place, and checking it out can be instructive. For most simple + matches, the number is quite small, but for patterns with very large + numbers of matching possibilities, it can become large very quickly + with increasing length of subject string. The match_limit_recursion + number is a measure of how much stack (or, if PCRE is compiled with + NO_RECURSE, how much heap) memory is needed to complete the match + attempt. + + When \O is used, the value specified may be higher or lower than the + size set by the -O command line option (or defaulted to 45); \O applies + only to the call of pcre[16]_exec() for the line in which it appears. + + If the /P modifier was present on the pattern, causing the POSIX wrap- + per API to be used, the only option-setting sequences that have any + effect are \B, \N, and \Z, causing REG_NOTBOL, REG_NOTEMPTY, and + REG_NOTEOL, respectively, to be passed to regexec(). + + +THE ALTERNATIVE MATCHING FUNCTION + + By default, pcretest uses the standard PCRE matching function, + pcre[16]_exec() to match each data line. PCRE also supports an alterna- + tive matching function, pcre[16]_dfa_test(), which operates in a dif- + ferent way, and has some restrictions. The differences between the two + functions are described in the pcrematching documentation. + + If a data line contains the \D escape sequence, or if the command line + contains the -dfa option, the alternative matching function is used. + This function finds all possible matches at a given point. If, however, + the \F escape sequence is present in the data line, it stops after the + first match is found. This is always the shortest possible match. + + +DEFAULT OUTPUT FROM PCRETEST + + This section describes the output when the normal matching function, + pcre[16]_exec(), is being used. + + When a match succeeds, pcretest outputs the list of captured substrings + that pcre[16]_exec() returns, starting with number 0 for the string + that matched the whole pattern. Otherwise, it outputs "No match" when + the return is PCRE_ERROR_NOMATCH, and "Partial match:" followed by the + partially matching substring when pcre[16]_exec() returns + PCRE_ERROR_PARTIAL. (Note that this is the entire substring that was + inspected during the partial match; it may include characters before + the actual match start if a lookbehind assertion, \K, \b, or \B was + involved.) For any other return, pcretest outputs the PCRE negative + error number and a short descriptive phrase. If the error is a failed + UTF string check, the offset of the start of the failing character and + the reason code are also output, provided that the size of the output + vector is at least two. Here is an example of an interactive pcretest + run. + + $ pcretest + PCRE version 8.13 2011-04-30 + + re> /^abc(\d+)/ + data> abc123 + 0: abc123 + 1: 123 + data> xyz + No match + + Unset capturing substrings that are not followed by one that is set are + not returned by pcre[16]_exec(), and are not shown by pcretest. In the + following example, there are two capturing substrings, but when the + first data line is matched, the second, unset substring is not shown. + An "internal" unset substring is shown as "<unset>", as for the second + data line. + + re> /(a)|(b)/ + data> a + 0: a + 1: a + data> b + 0: b + 1: <unset> + 2: b + + If the strings contain any non-printing characters, they are output as + \xhh escapes if the value is less than 256 and UTF mode is not set. + Otherwise they are output as \x{hh...} escapes. See below for the defi- + nition of non-printing characters. If the pattern has the /+ modifier, + the output for substring 0 is followed by the the rest of the subject + string, identified by "0+" like this: + + re> /cat/+ + data> cataract + 0: cat + 0+ aract + + If the pattern has the /g or /G modifier, the results of successive + matching attempts are output in sequence, like this: + + re> /\Bi(\w\w)/g + data> Mississippi + 0: iss + 1: ss + 0: iss + 1: ss + 0: ipp + 1: pp + + "No match" is output only if the first match attempt fails. Here is an + example of a failure message (the offset 4 that is specified by \>4 is + past the end of the subject string): + + re> /xyz/ + data> xyz\>4 + Error -24 (bad offset value) + + If any of the sequences \C, \G, or \L are present in a data line that + is successfully matched, the substrings extracted by the convenience + functions are output with C, G, or L after the string number instead of + a colon. This is in addition to the normal full list. The string length + (that is, the return from the extraction function) is given in paren- + theses after each string for \C and \G. + + Note that whereas patterns can be continued over several lines (a plain + ">" prompt is used for continuations), data lines may not. However new- + lines can be included in data by means of the \n escape (or \r, \r\n, + etc., depending on the newline sequence setting). + + +OUTPUT FROM THE ALTERNATIVE MATCHING FUNCTION + + When the alternative matching function, pcre[16]_dfa_exec(), is used + (by means of the \D escape sequence or the -dfa command line option), + the output consists of a list of all the matches that start at the + first point in the subject where there is at least one match. For exam- + ple: + + re> /(tang|tangerine|tan)/ + data> yellow tangerine\D + 0: tangerine + 1: tang + 2: tan + + (Using the normal matching function on this data finds only "tang".) + The longest matching string is always given first (and numbered zero). + After a PCRE_ERROR_PARTIAL return, the output is "Partial match:", fol- + lowed by the partially matching substring. (Note that this is the + entire substring that was inspected during the partial match; it may + include characters before the actual match start if a lookbehind asser- + tion, \K, \b, or \B was involved.) + + If /g is present on the pattern, the search for further matches resumes + at the end of the longest match. For example: + + re> /(tang|tangerine|tan)/g + data> yellow tangerine and tangy sultana\D + 0: tangerine + 1: tang + 2: tan + 0: tang + 1: tan + 0: tan + + Since the matching function does not support substring capture, the + escape sequences that are concerned with captured substrings are not + relevant. + + +RESTARTING AFTER A PARTIAL MATCH + + When the alternative matching function has given the PCRE_ERROR_PARTIAL + return, indicating that the subject partially matched the pattern, you + can restart the match with additional subject data by means of the \R + escape sequence. For example: + + re> /^\d?\d(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)\d\d$/ + data> 23ja\P\D + Partial match: 23ja + data> n05\R\D + 0: n05 + + For further information about partial matching, see the pcrepartial + documentation. + + +CALLOUTS + + If the pattern contains any callout requests, pcretest's callout func- + tion is called during matching. This works with both matching func- + tions. By default, the called function displays the callout number, the + start and current positions in the text at the callout time, and the + next pattern item to be tested. For example: + + --->pqrabcdef + 0 ^ ^ \d + + This output indicates that callout number 0 occurred for a match + attempt starting at the fourth character of the subject string, when + the pointer was at the seventh character of the data, and when the next + pattern item was \d. Just one circumflex is output if the start and + current positions are the same. + + Callouts numbered 255 are assumed to be automatic callouts, inserted as + a result of the /C pattern modifier. In this case, instead of showing + the callout number, the offset in the pattern, preceded by a plus, is + output. For example: + + re> /\d?[A-E]\*/C + data> E* + --->E* + +0 ^ \d? + +3 ^ [A-E] + +8 ^^ \* + +10 ^ ^ + 0: E* + + If a pattern contains (*MARK) items, an additional line is output when- + ever a change of latest mark is passed to the callout function. For + example: + + re> /a(*MARK:X)bc/C + data> abc + --->abc + +0 ^ a + +1 ^^ (*MARK:X) + +10 ^^ b + Latest Mark: X + +11 ^ ^ c + +12 ^ ^ + 0: abc + + The mark changes between matching "a" and "b", but stays the same for + the rest of the match, so nothing more is output. If, as a result of + backtracking, the mark reverts to being unset, the text "<unset>" is + output. + + The callout function in pcretest returns zero (carry on matching) by + default, but you can use a \C item in a data line (as described above) + to change this and other parameters of the callout. + + Inserting callouts can be helpful when using pcretest to check compli- + cated regular expressions. For further information about callouts, see + the pcrecallout documentation. + + +NON-PRINTING CHARACTERS + + When pcretest is outputting text in the compiled version of a pattern, + bytes other than 32-126 are always treated as non-printing characters + are are therefore shown as hex escapes. + + When pcretest is outputting text that is a matched part of a subject + string, it behaves in the same way, unless a different locale has been + set for the pattern (using the /L modifier). In this case, the + isprint() function to distinguish printing and non-printing characters. + + +SAVING AND RELOADING COMPILED PATTERNS + + The facilities described in this section are not available when the + POSIX interface to PCRE is being used, that is, when the /P pattern + modifier is specified. + + When the POSIX interface is not in use, you can cause pcretest to write + a compiled pattern to a file, by following the modifiers with > and a + file name. For example: + + /pattern/im >/some/file + + See the pcreprecompile documentation for a discussion about saving and + re-using compiled patterns. Note that if the pattern was successfully + studied with JIT optimization, the JIT data cannot be saved. + + The data that is written is binary. The first eight bytes are the + length of the compiled pattern data followed by the length of the + optional study data, each written as four bytes in big-endian order + (most significant byte first). If there is no study data (either the + pattern was not studied, or studying did not return any data), the sec- + ond length is zero. The lengths are followed by an exact copy of the + compiled pattern. If there is additional study data, this (excluding + any JIT data) follows immediately after the compiled pattern. After + writing the file, pcretest expects to read a new pattern. + + A saved pattern can be reloaded into pcretest by specifying < and a + file name instead of a pattern. The name of the file must not contain a + < character, as otherwise pcretest will interpret the line as a pattern + delimited by < characters. For example: + + re> </some/file + Compiled pattern loaded from /some/file + No study data + + If the pattern was previously studied with the JIT optimization, the + JIT information cannot be saved and restored, and so is lost. When the + pattern has been loaded, pcretest proceeds to read data lines in the + usual way. + + You can copy a file written by pcretest to a different host and reload + it there, even if the new host has opposite endianness to the one on + which the pattern was compiled. For example, you can compile on an i86 + machine and run on a SPARC machine. When a pattern is reloaded on a + host with different endianness, the confirmation message is changed to: + + Compiled pattern (byte-inverted) loaded from /some/file + + The test suite contains some saved pre-compiled patterns with different + endianness. These are reloaded using "<!" instead of just "<". This + suppresses the "(byte-inverted)" text so that the output is the same on + all hosts. It also forces debugging output once the pattern has been + reloaded. + + File names for saving and reloading can be absolute or relative, but + note that the shell facility of expanding a file name that starts with + a tilde (~) is not available. + + The ability to save and reload files in pcretest is intended for test- + ing and experimentation. It is not intended for production use because + only a single pattern can be written to a file. Furthermore, there is + no facility for supplying custom character tables for use with a + reloaded pattern. If the original pattern was compiled with custom + tables, an attempt to match a subject string using a reloaded pattern + is likely to cause pcretest to crash. Finally, if you attempt to load + a file that is not in the correct format, the result is undefined. + + +SEE ALSO + + pcre(3), pcre16(3), pcreapi(3), pcrecallout(3), pcrejit, pcrematch- + ing(3), pcrepartial(d), pcrepattern(3), pcreprecompile(3). + + +AUTHOR + + Philip Hazel + University Computing Service + Cambridge CB2 3QH, England. + + +REVISION + + Last updated: 21 February 2012 + Copyright (c) 1997-2012 University of Cambridge. |